The present invention relates to computer generated graphics, in particular, the modeling and rendering of photorealistic graphics such as facial expressions using a computer.
Computer graphics are used in many different applications including computer games, movies and web pages. With the capability of more powerful computers, photorealistic graphics are becoming more desired in order to provide a more realistic experience to the computer user.
One particular area of focus has been in area of synthesized photorealistic expressions of a human face. One known technique includes “expression mapping” (also called performance driven animation), which has been a popular method to generate facial animations. Using this method, a performer is located in front of a computer that monitors selected points (“feature points”) of the performer's face. Motions of the feature points are then used to drive the feature point motions of a different person's synthesized face using the computer. However, one shortcoming of this method is that the method does not produce expression details such as wrinkles caused by skin deformation in the synthesized face. Thus, although the synthesized face includes, for example, eye and mouth movements for various expressions, the synthesized face lacks photorealistic qualities because the corresponding wrinkles, folds, dimples and the like present in the skin for instance in the person's forehead, cheeks, chin, etc. are not consistent with the person's overall expression.
Accordingly, a systematic method for rendering photorealistic facial expressions that include appropriate changes in the skin for a given expression would be very beneficial. Aspects of such a method would be useful in other rendering applications as well.